"There can only be one assessment of what happened in Kiev and Ukraine as a whole - this was an anti-constitutional takeover and armed seizure of power," Mr Putin said of Mr Yanukovych's ousting.

Crucially, Mr Putin said this meant Russian intervention in Ukraine was justified because Moscow had received a request for protection of its citizens from Mr Yanukovych.

"We have a direct request from the acting and legitimate - as I have already said - president Viktor Yanukovych - about using armed forces to protect the lives, health and freedom of Ukrainian citizens," Mr Putin said.

Mr Yanukovych has taken refuge in southern Russia after crossing from Ukraine in a way that has not been made public.

Moscow wants the current government in Kiev to be replaced by a broad coalition representing what it calls "all political forces" in the country, with presidential elections to be held in December.

'He's not fooling anyone': Obama

Speaking after the Russian president's remarks, Mr Obama said there was a "strong belief" around the world that Russia was violating international law even if Mr Putin had a "different set of lawyers" or "interpretations".

"I don't think that's fooling anybody," he said.

"I think everybody recognises that although Russia has legitimate interests in what happens in a neighbouring state that does not give it the right to use force as a means of exerting influence."